1. Field of the Invention
The present invention relates to a thermal-expansion compensator for compensating the thermal expansion of a headlamp unit of a light module. The present invention also relates to a corresponding light module.
2. Related Art
Light modules in headlamps are used for emitting light for illuminating the area in front of a vehicle, wherein the emitted light could be a low beam featuring a cut-off line. Here it is provided that the cut-off line of the low beam does not exceed a specified angle relative to the horizontal. However, the thermal behavior of the headlamp housing can lead to a not insignificant displacement of the cut-off line relative to the horizontal, because the receptacle element leaves its specified position due to the thermal expansion behavior of the housing, resulting in a tilting of the carrier frame and consequently a tilting of the light module, so that the cut-off line likewise leaves its specified angle or its specified height.
FEM simulations can be performed for overcoming impermissible tilting of the light module in the housing of the headlamp. However, numerical modeling of the complex thermomechanical behavior of a headlamp is often inadequate. An advantageous, thermomechanically stable arrangement of the receptacle elements for holding the light module in the housing of the headlamp can indeed minimize tilting of the light module, but disadvantageous thermal relationships of the housing can nevertheless lead to undesired tilting of the light module. For example, superimposing the thermal effect of the housing of the headlamp by the ambient temperature and also radiant heat from the engine forms a complex temperature field, so that thermal effects also on parts of the housing are taken into account only to a limited extent.
Thermal-expansion compensators for compensating the thermal expansion of a light module are generally known. They are used to compensate thermal expansions, that is, changes in geometry of a light module. When light modules are operating, they are subjected to different working temperatures. The temperatures and thermal-expansion coefficients of the materials being used produce different thermal expansions, that is, different geometrical dimensions for the headlamp unit.